Downhole coiled tubing latch

Abstract

A downhole coiled tubing latch for positive latching to a drill pipe while pumping fluids. The apparatus comprises a housing positioned in the drill pipe with a slidable mandrel positioned in the housing. The apparatus further comprises a latch stinger which can be lowered on a coiled tubing and sealingly engaged with the mandrel and the housing. When weight is set down, the stinger and mandrel are moved downwardly which actuates latch fingers on the mandrel which latchingly engage a groove on the stinger to positively hold the stinger in place while fluids are pumped therethrough. One or more pressure balance pistons are used to help hold the apparatus in a latched position when pressure is applied. When weight is picked up, a spring returns the mandrel to the unlatched position so that the stinger may be removed.

What is claimed is: 
     
       1. A downhole apparatus comprising: housing means for connecting to a drill pipe;   a mandrel slidably disposed in said housing means;   stinger means for positioning in said housing means and allowing pumping of fluid therethrough; and   latching means for latching said stinger means to said housing means when said stinger means is moved downwardly in said housing means.   
     
     
       2. The apparatus of claim 1 wherein said latching means comprises: a latch finger pivotally disposed on said mandrel and adapted for latchingly engaging a latching groove on said stinger means.   
     
     
       3. The apparatus of claim 2 wherein said latch finger comprises a lug thereon for extending into said latching groove when in a latching position. 
     
     
       4. The apparatus of claim 2 further comprising biasing means for biasing said mandrel toward an unlatched position. 
     
     
       5. The apparatus of claim 4 wherein said biasing means comprises: a shoulder on said mandrel;   a shoulder on said housing means; and   a spring disposed between said shoulder on said mandrel and said shoulder on said housing means.   
     
     
       6. The apparatus of claim 2 further comprising a piston adapted on said mandrel for providing a downward force on said mandrel when pressure is applied to said piston. 
     
     
       7. The apparatus of claim 6 wherein said piston is in fluid communication with a central opening through said stinger means. 
     
     
       8. The apparatus of claim 2 further comprising sealing means for sealing between said stinger means and said mandrel. 
     
     
       9. The apparatus of claim 1 wherein said stinger means is adapted for attachment to a coiled tubing string. 
     
     
       10. A downhole apparatus comprising: a housing adapted for positioning in a drill pipe and defining a central opening therethrough;   a mandrel assembly slidably disposed in said housing and defining a mandrel central opening therethrough;   a stinger positionable in said mandrel central opening; and   latching means for latchingly engaging said stinger when said stinger is moved downwardly.   
     
     
       11. The apparatus of claim 10 wherein: said mandrel defines an aperture therein; and   said latching means comprises a latch finger pivotally disposed in said aperture.   
     
     
       12. The apparatus of claim 11 wherein: said stinger defines a latching groove thereon; and   said latch finger has a lug thereon adapted for extending into said latching groove when said finger is in the latched position.   
     
     
       13. The apparatus of claim 12 wherein said latch finger is pivoted to said latched position as said mandrel and said stinger are moved axially in one direction in said housing and pivoted to an unlatched position as said mandrel and said stinger are moved axially in an opposite direction in said housing. 
     
     
       14. The apparatus of claim 13 further comprising biasing means for biasing said mandrel toward an unlatched position. 
     
     
       15. The apparatus of claim 14 wherein said biasing means comprises a spring disposed between said housing and said mandrel. 
     
     
       16. The apparatus of claim 14 wherein said latch finger is pivoted to an unlatched position in response to movement of said mandrel resulting from said biasing means. 
     
     
       17. The apparatus of claim 10 wherein said mandrel comprises a piston adapted for exerting a downward force on said mandrel when pressure is applied thereto. 
     
     
       18. The apparatus of claim 17 wherein said piston is one of a plurality of pistons. 
     
     
       19. The apparatus of claim 10 further comprising sealing means for sealing between said stinger and said mandrel when said stinger is disposed in said mandrel. 
     
     
       20. The apparatus of claim 10 wherein said stinger is adapted for connection to a coiled tubing string. 
     
     
       21. A method of pumping fluid into a drill pipe comprising the steps of: positioning a latch housing with a slidable latch mandrel therein in a drill pipe in a well bore;   positioning a stinger in said mandrel and latch housing;   setting down weight on said stinger to apply an axial force for moving said stinger and mandrel in said latch housing; and   latchingly engaging said mandrel and said stinger in response to said movement.   
     
     
       22. The method of claim 21 further comprising the step of sealing between said stinger and mandrel when said stinger and mandrel are latched. 
     
     
       23. The method of claim 21 further comprising applying fluid pressure to a piston on said mandrel to provide a force on said mandrel for preventing pumping of said mandrel upwardly. 
     
     
       24. The method of claim 21 further comprising the step of biasing said mandrel such that said mandrel and stinger are moved to an unlatched position when weight is picked up on said stinger.